The present invention relates generally to electrical connectors, and more specifically to an electrical connector having a conductive contact configuration that minimizes non-target contact.
Electrical connectors are fundamental to routing electrical connections between separate electrical circuits. For example, information stored in a stand-alone memory component may be accessed by a processor after electrical connection is made through an electrical connector. Typically, this electrical connection is made by electrical contact with conductive contact pads on a target circuit. The electrical connector generally provides contact structures, such as resilient, conductive filaments, that are aligned with, and capable of, touching each of the contact pads.
In many cases, the target circuit includes contact pads that are directly connected to an integrated circuit, such as a memory chip fabricated by microlithography on a silicon wafer. A non-conductive, protective bead is often used to position the memory chip relative to the contact pads. The bead is commonly in the form of a polymerized organic resin, such as an epoxy resin. An epoxy bead stably adheres the memory chip to a substrate, in a precise conductive relation to contact pads formed on the substrate. Furthermore, the epoxy bead electrically insulates the memory chip from unwanted conductive connection and protects the memory chip from chemical, electrical, and physical damage.
Despite the important roles played by an epoxy bead, the presence of the bead may cause problems. For example, the epoxy bead is typically positioned immediately adjacent the contact pads of the target circuit, to minimize the size, and thus cost, of the target circuit. Therefore, as the connector or target circuit is positioned for conductive contact, one or more of the conductive contact structures of the connector may contact the epoxy bead, which usually occurs as a raised structure relative to the contact pads. This contact may occur during mating of the connector with a receptacle, or during positioning of the target circuit (for example, where the target circuit is on a removable module such as an ink supply of an inkjet printing mechanism such as a printer). The contact with an epoxy bead may preclude proper conductive contact between the connector and the appropriate contact pad(s) and/or may damage the memory chip under the epoxy bead.
Increasing the overall size of the target circuit allows the epoxy bead and contact pads to be spaced farther apart and tends to lessen the possibility of stable, non-conductive contact between the connector and the epoxy bead. However, increased spacing within the target circuit generally increases the cost of the target circuit. In particular, gold is commonly used to form each contact pad because of desirable properties of gold, such as high conductivity and low propensity for corrosion. With increased target circuit size, more gold will be required to form the contact pads.
More precise alignment between the conductive contact structures of the connector and the contact pads may help eliminate some of the undesired contact between the epoxy bead and the connector. For example, a positioning system for a connector is described in U.S. patent application Ser. No. 09/925,400 titled Electrical Connector with Biased Positioning, naming Scott D. Sturgeon and David C. Johnson as inventors, and filed Aug. 9, 2001, the subject matter of which is incorporated herein by this reference. However, a more precisely defined mated position of the connector may not be sufficient to avoid unwanted non-conductive and/or damaging contact with the epoxy bead when the epoxy bead is closely spaced from the contact pads or is substantially raised above the target circuit""s surface. Therefore, an electrical connector capable of minimizing undesired contact with a non-conductive bead or other non-target structure would still be useful.
The present invention provides an electrical connector configured for minimized contact with non-target structures of a target circuit, and a printing mechanism that uses the electrical connector for conductive connection between circuit portions of the printing mechanism. The connector includes a housing for positioning the connector in conductive contact with the target circuit. An electrically conductive contact filament is mounted on the housing and includes a proximal portion extending from the housing and a contact portion for electrically contacting the target circuit. An intermediate portion is formed to circumnavigate the non-target structure and joins the proximal and distal portions.